Photographic emulsions containing an antifoggant and antiplumming agent



United tates Patent PHOTOGRAPHIC EMULSIONS CONTAINING AN ANTIFOGGANT ANDANTIPLUMMING AGENT Jean Barbier, Paris, France, assignor to EastmanKodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing.Application November 5, 1958 Serial No. 771,954

4 Claims. (CI. 96-67) given. This is commonly called fog, and sometimes.

called chemical fog where it is necessary to distinguish between it andthe effects of accidental exposure to radia tion; in this invention, Iam not concerned with the latter.

the degree of development.

1 din.

tographic emulsions by storage at increased temperature or humidity, orboth. It is, of course, desirable to have emulsions as stable aspossible under the conditions of 1 high temperature and humidity whichmay occur in tropical.climates, for example. Fog usually appears overthe whole area of the sensitive coating, but when severe, it frequentlyis non-uniform. Fog may also be caused by exposure to chemicals, forexample, hydrogen sulfide and other reactive sulfur compounds, hydrogenperoxide, vapor, and strongly reducing materials. While antifoggants andstabilizers may protect, to some extent, against such effects, it isnormally understood that an anti-foggant protects against spontaneousgrowth of fog during prolonged storage or storage at high temperaturesand humidities, or during development to maximum contrast and speed, orboth.

Silver halide emulsions, especially those used on paper supports, areoften subject, on processing and especially on glazing, to that form ofimage degradation known as plumming. Compounds which reduce this effectare called anti-plumming agents. f

It is, therefore, an object of my invention to provide photographicsilver halide emulsions stabilized against the formation of fog; Anotherobject is to provide photographic silver halide emulsions which giverise to prints whichcan be hot glazed or ferrotyped without objectionable plumming. Still another object is to provide photographicsilver halide emulsions having improved sensitivity withoutobjectionable increase in fog when said emulsions are stored underadverse conditions of temperature and humidity. Other objects willbecome apparent from a consideration of the following description andexamples.

According to the present invention l provide a lightquinolino1":2':4,:5-triazole(1:2:4)-3-thiol, or its watersoluble' -saltsand4-methy1-7-diethylaminocoumarin;'

sensitive silver "halide emulsion containing 1:2'-dihydropound which canfbeemployedrin my invention;- include-" "ice alkali metal salts, 'suchas sodium; potassium, etc., the

ammonium salt, orsubstituted ammonium (e.g., triethyl: ammonium,triethanolamm'onium, pyridinium, etc.) salts.

Theabove triazole compound which can be used in practicing my inventioncan be represented by the following formula: i

N Hs-b=N. The coumarin compound which can be employed in practicing myinvention can advantageously he represented by the'following formula: AH CH8 In Williams US. application Serial No. 655,472, filed April 29,1957, now U. S. Patent 2,887,378, issued May 19,1959, there is describeda method of stabilizing pho tographic silver halide emulsions and at thesame time preventing plummingduring the hot-glazing of photo- I V o yFog depends both on the emulsion and the conditions Jraphlc puntsThigmgflwd compnses addl g certam of development; for a given emulsionit increases with r 7 With constant development conditions, it tends toincrease with time, temperature and relative humidity of storageconditions, it is common practice to make accelerated tests of thestability of phocomplex triazole compounds to the photographic emulsionsduring the preparation thereof. Among the triazole compoundsdescribed-in Serial No. 655,472 is the particular triazole compoundrepresented above. However, I

when suificient triazole compound is added to prevent fogging of thephotographic emulsions, it has been found that there-is a certain speedloss resulting from the partial-desorption of the spectral sensitizingdy es customarily employed in sensitizing photographic emulsions. It hasbeen found that'the above coumarin compound can be :advantageouslyemployed in -combination with the triazole compound to'obtaiu both thedesired anti foggant elfect and antiplumming effect. According to mymethod, thetriazole compound can be employed in' to a synergistic elfectof the type sometimes encountered A in catalytic reactions. e

-It is interesting to note that other coumarincomj pounds, such'asfl-methylumbelliferone and 4-methyl-7i aminocoumarin, have been tried incombination with the triazole compoundof'my invention, but the usefuleffect illustrated below has not been obtained. On the other hand, theuse of conventional antifoggant compounds, such' as 5-methylbenzotriazole and l-phenyl-S-mercap'itotetrazole, does not provide effectscomparable to the triazole compound used in my invention. he preparationof silver halide emulsions involves three separate operations: '(1) theemulsifieation "and digestion of ripening of the silver halide, (2) thefreeing of the emulsion from excess soluble salts, usuallyby washing,and (3) the seconddigestion or after ripening to obtain increasedsensitivity. (Mees, The Theoryof the' Photographic Process 1942).) Ifprefer toga thestabiliziiig agents aft the final digestien or after;

ripening, althoughthey cani advantageously-be added,

prior to digestion.

' The photographic emulsions used in practicing my 7 2,928,735, PatentedMar. 15, 19 0 3 vention are generally of the developing-out type; also,it is to be understood that photographic emulsions of varying silverhalide content can advantageously be used. The particular combinationsused' in my invention have been found particularly useful when employedin conjunction with gelatino-silver-chloride emulsions, al thoughtheycan advantageously be'employed for treating other silver halideemulsions, such as gelatino-silverchlorobrornide, bromide,chlorobromiodide, etc.

The compounds of my invention can advantageously 'be added to theemulsions in the form of their aqueous solutions or as solutions in awater-miscible organic solvent such as acetone, etc. The combinationsshould be uniformly mixed with the emulsions in order to assure uniformresults in the finished emulsions. If desired, the compounds can be,added before the final step of fafterripening, or they can be added to,the emulsions immediately prior to coating; as. indicated. above; 7

The most useful, concentration of the triazole and GramsN-methyl-p-aminophenol sulfate 1.7 Hydroquinone 7.0 Sodium sulfite,anhydrous 25.0 Sodium carbonate, anhydrous 35.0 Potassium bromide 0.45

Water to make 1 liter.

The results obtained by processing the above emulsions are given in thefollowing table. In the table, the sensitometric data were obtained fromthe coatings which were developed for 2 minutes.

Table Fog-Deva]. Time. Sensltometrlc Data Coatln Addenda (g./mol. Ag) al v g 2' 15' D Rel. Rel.

max. Speed Contrast (a) None 04 20 1. 54 100 100 (b) 1 :2;ilciliiiyldgoquinollno-l' :2 :4:5-triazole-(1:2:4)- 10 .16 .20 1.72 1103- 0 4-methyl-7-diethylaminocoumarin (4.0) 12 15 20 1. 62 904-111ethyl-7-diethylaminocoumarlu (8.0)...- 12 15 20 1.66 90 100 1:2-dihydroquino1in0 1':2:4 :5 -triaz0le- (1:2:4)- 02 04 06 1. 82 903-thiol (0.4) plus 4-methyl-7-dlethylamlnocoumarin (4.0).fi-methylbenzotriazole (8.0) .02 .12 .18 1.58 90 S-methylbenzottiazole(8.0) plus 4-n1ethyl-7- .04 .08 11 1. 00 90 120 diethylaminocoumarin(4.0). 1' :2 dihydroquinolino- 1 :2 24:5 -trlazole- (1 :2:4)- 02 06.10 1. 68 90 110 3-thiol (0.4) plus B-methylbenzotrlazole (8.0).

coumarin compounds can be varied, depending upon the particular silverhalide being treated, the presence or absence of other emulsion addenda,etc. The most useful concentration for a particular emulsion can bedetermined by adding a small amount, such as 1-2 grams per mole ofsilver halide, to the emulsion and then adding varying amounts of theotheringredients to separate portions of the same emulsion. Theemulsions can then be coated, exposed in a sensitometer and then glazedto provide prints. The maximum density and fog in each of the prints canthen be measured. In general, I have found that from about 0.1 to 1.0gram per'mole of silver (or silver halide) of the triazole compound isquite useful. In like manner, I have found that from about 2.0 V

most beneficial effects, i.e., with a minimum amount of fog and amaximum density. i

The following examples will serve to illustrate the unique effect of thetriazole compound and the coumarin compound of m invention when employedsimultaneousl'yin an ordinary photographic silver chloride emulsion.

Instead of adding the triazole and coumarin com pounds directly to thephotographic emulsions, it is sometimes desirable to incorporate them ina separate colloid layer which is placed in contact with the silverhalide emulsion layer. Under such conditions, of course, it is advisableto use a higher concentration of these compounds than indicated above.

The compoundsof my invention function either in acid or alkalinephotographic silver halide emulsions. In alkaline emulsions,water-soluble salts of the mercaptotriazole compound are formed to someextent, although it is to be understood that the salts of this compoundcan be used directly in photographic silver halide emulsions. Alkalimetal salts of this mercapt'otria zole can be formed by simplycontacting such mercapto compound with an aqueous solution of an alkalimetal hydroxide, such as sodium hydroxide, potassium hydroxide, etc. Theam- The emulsion was divided into; several batches and the separatebatches treated with the addenda, identified in 'the following table;the concentration of the addenda being given in the parenthesesfollowing the chemical name, The'emul'sions were then exposed in theusual manner, n a sensitometer and separate sections of each moniumsalts of the mercapto compound can be prepared by simply contacting saidmercapto compound with ammonia or an organic amine, such as pyridine,triethylamine, triethanolamine, aniline, etc.

. The emulsions can be chemically sensitized by any of the acceptedprocedures. The emulsions can .be digested with naturallyactivefgelatin, jor sulfur compounds can be added such as thosedescribed in Sheppard US. Patents 1,574,944, issued March 2, 1926,and1,623,499, issued April. 5, 1927, and Sheppard and Brigham US.

7 Patent 2,410,689, issued November 5, 1946.

coating were developed for 2. 15 and 30 minutes as indi-,

catedI in thetable. Thei fog developed by each of these processeslfis.shown. The relative speed, based. on; untreated emulsion and. relativecontrast for each; of the coatings is also shown. T he.maximum-densityfor each of the coatings, after gla2ing at 80 C. is. alsoindicated.

In the following table there. is also shown the effect The emulsions canalso be treated with salts of the noble metals such as ruthenium,rhodium, palladium,

iridium, and platinum. Representative compounds are ammoniumchloropalladate, potassium chloroplatinate, and sodium chloropalladite,which are used for sensitiz: ingin' amounts below that. whichproducesany substantial fog inhibition, as" described in Smith andTrivelli U.S. Patent.2,448,060, issued August 31, 1948, and asantifoggants inv higher amounts, as described in Trivelli and Smith U.S.Patentsl2,566,245, issuedAugust 28, 1951,

and. 2,566,263,isssucdAugust 28,. 1951..

The emulsions can also be chemically sensitized with gold salts asdescribed in Waller and Dodd U.S. Patent 2,399,083, issued April 23,1946, or stabilized with gold salts as described in Damschroder U.S.Patent 2,597,856,

issued May 27, 1952, and Yutzy and LeermakersUS. Patent 2,597,915,issued May 27, 1952. Suitable com pounds are potassium chloroaurite,potassium aurithiocyanate, potassium chloroaurate, auric trichloride and2-aurosulfobenzothiazole methochloride.

The emulsions can also be chemically sensitized with reducing agentssuch as stannous salts (Carroll U.S. Patent 2,487,850, issued November15, 1949), polyarnines,

such as diethylene triamine (Lowe and Jones U.S. Patent 2,518,698,issued August 15, 1950), polyamines, such as spermine (Lowe and AllenU.S. Patent 2,521,925, issued September 12, 1950), orbis(fl-aminoethyl)sulfide and its water-soluble salts (Lowe and JonesU.S. Patent 2,521,- 926, issued September 12, 1950).

The emulsions can also be optically sensitized with cyanine andmerocyanine dyes, such as those described in Brooker U.S. Patents1,846,301, issued February 23, 1932; 1,846,302, issued February 23,1932; and 1,942,- 854, issued January 9, 1934; White U.S. Patent 1,990,-507, issued February 12, 1935; Brooker and White U.S. Patents 2,112,140,issued March 22, 1938; 2,165,338, issued July 11, 1939; 2,493,747,issued January'lO, 1950; and 2,739,964, issued March 27, 1956; Brookerand Keyes U.S. Patent 2,493,748, issued January 10, 1950; Sprague U.S.Patents 2,503,776, issued April 11, 1950, and 2,519,- 001, issued August15, 1950; I-Ieseltine and Brooker U.S. Patent 2,666,761, issued January19, 1954; Heseltine U.S. Patent 2,734,900, issued February 14, 1956; VanLare U.S. Patent 2,739,149, issued March 20, 1956; and Kodak LimitedBritish Patent 450,958, accepted July 15, 1936.

The emulsions may also contain speed-increasing compounds of thequaternary ammonium type of Carroll. U.S. Patent 2,271,623, issuedFebruary 3, 1942; Carroll and Allen U.S. Patent 2,288,226, issued June13, 1942; and Carroll and Spence U.S. Patent 2,334,864, issued November23, 1943; and the polyethylene glycol type of Carroll and Beach U.S.Patent 2,708,162, issued May 10, 1955.

In the preparation of the silver halide dispersions em ployed forpreparing silver halide emulsions, there, may be employed as thedispersing agent for the silver halide in its preparation, gelatin orsome other colloidal material such as colloidal albumin, a cellulosederivative, or a synthetic resin, for instance, a polyvinyl compound.Some colloids which'may be used are polyvinyl alcohol or a hydrolyzedpolyvinyl acetate as described in Lowe U.S. Patent 2,286,215, issuedJune 16, 1942; a far hydrolyzed cellulose ester such as celluloseacetate hydrolyzed to an acetyl content of 19-26%; a water-solubleethanolamine cellulose acetate as described in Yutzy U.S. Patent2,322,085, issued June 15, 1943; a polyacrylamide having a combinedacrylarnide content of 30-60% and a specific viscosity of 025-15 on animidized polyacrylamide of like acrylamide content and viscosity asdescribed in Lowe, Minsk and Kenyon U.S. Pateut 2,541,474, issuedFebruary 13, 1951; zein as described in Lowe U.S. Patent 2,563,791,issued August 7, 1951; a vinyl alcohol polymer containing cyano-acetylgroups such as vinyl alcohol vinyl cyanoacetate copolymer'as describedin Unruh and Smith U.S. Patent 2,768,154, issued October 23, 1956; or aurethane carboxylic acid compound of the type described in Unruh, Smithand Priest U.S. Patent 2,808,331, issued October 1, 1957.

If desired, compatible mixtures of two or more of these colloids may beemployed for dispersing the silver halide in its preparation.

The silver halide emulsions of zny invention can be.

coated on any of the conventional, flexible photographic supports, suchas paper, polyvinyl resin film, polyester film, etc. However, theemulsions'of my invention are particularly useful in preparingphotographic prints, in which case paper would ordinarily be used as thesupport.

' Other fibrous supports than paper can also be employed.

lino-1':2':4:5-triazole-(1:2:4)-3-thiol and a water-soluble salt of1':2-dihydroquinolino-1':2':4:5-triazole(1:2:4)-

3-thiol.

2. A photographic silver chloride-emulsion containing4-methyl-7-diethylarninocoumarin and a compound selected from'the groupconsisting of 1':2'-dihydroquinolino-1:2:4:5-triazole-(1:2:4)-3-thioland a water-soluble salt of1':2-dihydroquinolino1':2:4:5-triazole(1:2:4)-

3-thiol. 1

3. A photographic gelatino-silver-chloride developingout emulsioncontaining astabilizing amount of 4-methyl- 7-diethylaminocoumarin andsufiicient compound selected from the group consisting of1:2:-dihydroquinolino- 1':2':4:5-triazole-(l:2:4)-3-thiol and awater-soluble salt of 1':2' dihydroquinolino 1:2':4:5 triazole(1:2:4)-3-thiol, to prevent plumming of said photographic emulsion.

4. A photographic element comprising asupport and a photographic silverhalide emulsion containing 4-methyl- 7-diethylaminocoumarin and acompound selected from the group consisting of1':2-dihydroquinolino-1':2:4:5- triazole(1:2:4)-3-thiol and awater-soluble salt of 1:2-dihydroquinolino-1':2:4:5-triazole(l:2:4)-3-thiol.

. 2,649,375 Davis -1 Aug. 18, 1953 2,887,378" Williams v May 19, 1959'

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION CONTAINING4-METHYL-7-DIETHYLAMINOCOUMARIN AND A COMPOUND SELECTED FROM THE GROUPCONSISTING OF1'':2''-DIHYDROQUINOLINO-1'':2'':4:5-TRIAZOLE-(1:2:4)-3-THIOL AND AWATER-SOLUBLE SALT OF1'':2''-DIHYDROQUINOLINO-1'':2'':4:5-TRAZOLE(1:2:4)3-THIOL.